Command line arguments parser rewrite and help clarification

Help for dnf commands is now divided into two parts - "General DNF options"
and "Command specific options". This commit also prevents mixing
options from these two distinct groups together which was previous behavior
for argument from mutually exclusive groups (e.g. --best/--nobest).
Also the command specific options are printed later - under the general ones,
so the user sees them on the screen without need to scroll up.

Due to the problems with groups behaviour in python argparse, we need to avoid
using "inheritance" in argument definition.
Basically the problem is, that when you use parents=[] in ArgumentParser
constructor, mutually exclusive groups are forgotten. See
https://bugs.python.org/issue16807
https://bugs.python.org/issue25882

https://bugzilla.redhat.com/show_bug.cgi?id=1659328

dnf/cli/commands/group.py

@@ -51,7 +51,7 @@ class GroupCommand(commands.Command):
 
     def _canonical(self):
         # were we called with direct command?
-        direct = self.direct_commands.get(self.opts.command[0])
+        direct = self.direct_commands.get(self.opts.command)
         if direct:
             # canonize subcmd and args
             if self.opts.subcmd is not None:

dnf/cli/commands/module.py

@@ -307,5 +307,5 @@ def check_required_argument(self):
         if self.opts.subcmd[0] not in not_required_argument:
             if not self.opts.module_spec:
                 raise CliError(
-                    "dnf {} {}: too few arguments".format(self.opts.command[0],
+                    "dnf {} {}: too few arguments".format(self.opts.command,
                                                           self.opts.subcmd[0]))